不同立地条件下胡杨叶片稳定碳同位素组成及水分利用效率的变化

研究了黑河流域下游额济纳荒漠河岸不同立地条件下胡杨(Populus euphratica Olivier)叶片稳定碳同位素组成及水分利用效率的变化特征.结果表明:5个典型样地中,胡杨叶片δ13 C值在(-25.80±0.05)‰～(-29.19±0.05)‰间变化,均值为(-27.70±0.13)‰;就生长季胡杨叶片δ13 C均值而言,沙丘样地具有最高的δ13 C值,其次为戈壁样地,最低值出现在河岸低地.样地间δ13 C值的差异主要是由样地间土壤含水量和地下水埋深的不同导致的;整个生长季胡杨叶片δ13 C值在样地间表现为2种变化趋势.5个典型样地生长季胡杨水分利用效率在(60.41±0.47)～(95.46±0.47)μmolCO2.(mmolH2O)-1间波动变化,其平均值为(75.69±1.37)μmolCO2.(mmol H2O)-1,从水分利用效率波动范围和平均值可以看出,胡杨是个具有高水分利用效率的物种.从河岸低地到河岸沙堆再到戈壁、沙丘,随着土壤含水量逐渐下降,地下水埋深逐渐加深,胡杨逐渐提高了其水分利用效率.

Variations of Foliar Stable Carbon Isotope Composition and Water Use Efficiency in Populus euphratica for Different Plots

In this paper,the variations of foliar stable carbon isotope composition(δ13C) and water use efficiency in P.euphratica in different plots are studied.It is found that the values of foliar stable carbon isotope composition(δ13C) of P.euphratica in the five plots vary from(-25.80±0.05)‰ to(-29.19±0.05)‰,with a mean of(-27.70±0.13)‰.The average δ13C value is the highest in the dune plot,followed by that in gobi plot,with a lowest in riparian plot.The difference in δ13C value among different plots is caused by discrepancy in soil water content and groundwater depth.There are two trends of foliar δ13C values during the whole growing season.Water use efficiency in P.euphratica in the five plots during the growing season varies from(60.41±0.47) to(95.46±0.47)μmolCO2·mmolH2O-1,with a mean of(75.69±1.37)μmolCO2·mmolH2O-1.The range and average of water use efficiency indicate that P.euphratica is a species with higher water use efficiency.From riparian lowland,sandpile,Gobi plot to Dune plot,with reduction of soil water content and lowering of groundwater depth,the water use efficiency is improved gradually.